Metering unit for liquid fuel burners



Jan. 4, 1955 H. B. HOLTHOUSE, SR, ET AL 2,698,744

METERING UNIT FOR LIQUID FUEL BURNERS 3 She'ets-Sheet l Filed April 20. 1949 JNVENTOE B. H carib -m Ha'rry Harry B. HolfhousqJr. @2 4 A. 9'

1955 H. B. HOLTHOUSE, sR., ET AL 2,698,744

METERING UNIT FOR LIQUID FUEL BURNERS Filed April 20. 1949 3 Sheets-Sheet 2 JANE/Wm? Harry B. Holfhouse, 5:: Harry B. Ho/Hn'ouse, Jr

1955 H. B. HOLTHOUSE, 5a., ETAL 2,698,744

METERING UNIT FOR LIQUID FUEL BURNERS 3 Sheets-Sheet 3 Filed April 20. 1949 b I N VEN 70/2 Harry B- Hvli'house, 5r. Hkzrry B- Hoflho se, Jr W KM avg.

United States Patent Harry B. Holthouse, Sr., and Harry B. Holthouse, Jr.,

Chicago, Ill., assignors, by mesne assignments, to Harry B. Holthonse Application April 20,- 1949, Serial No. 88,601

2 Claims. (Cl. 261-24) This invention relates generally to liquid fuel burners of internal-combustion type and in particular to a fuel supply system for such a burner adapted to meter fuel for burning in response to the supply of combustion air.

An object of this invention is to provide an improved space heater of internal-combustion type.

A further object of this invention is to provide a liquid fuel burner having ablower for supplying combustion air and a fuel supply line, in which fuel is metered to the fuel line in response to the supply of combustion air.

Yet another object of this invention is to provide a liquid fuel burner having a blower for supplying combustion air under pressure and a fuel line, in which fuel from a source of fuel supply is continuously metered to the fuel line in response to the pressure of the combustion air to maintain a predetermined air to fuel ratio at the burner.

A still further object of this invention is to provide a liquid fuel burner having a fuel supply system capable of acting on the fuel at a low pressure so that the fuel is broken up into a bubble or foam form and supplied in such form to the burner. 7

Another object of this invention is to provide a liquid fuel burner having a blower for supplying combustion air under pressure and a fuel system, in which a fuelmetering device in the fuel system, responsive in opera tion to the pressure of the combustion air, is adjustable to effect a desired air to fuel ratio at the burner, and capable of maintaining such air to fuel ratio such that the burner is adapted to operate with a modulated flame over a wide range of burner operation.

Still a further object of this invention is to provide a liqu1d fuel burner having a variable speed blower for supplying combustion air and a fuel line, in which a fuelrnetermg device -is adapted to supply fuel to the fuel line in response to speed variations of the blower to maintain a desired air to fuel ratio at the burner.

A feature of this invention is found in the provision of a fuel-metering device for a liquid fuel burner having a blower for supplying combustion air under pressure and a fuel line, in which a casing is formed with a pair of separate fuel chambers having fuel communication at a positlon below the level of the fuel therein. An upright tubular member in a first one of the fuel chambers is formed with a longitudinally extended fuel-metering slot, with the lower end of the slot terminating substantially at the fuel level in such chambers, and the lower end of the tubular member being connected with the fuel line. The second chamber, above its fuel level, is in air communication with the combustion air so that on an increase in the pressure of the combustion air, the level of the fuel in the first chamber is elevated so as to effect a flow of fuel through the metering slot into the fuel line. The two chambers, above their fuel levels, may be provided with atmospheric bleeder valves to vary the effective action of the air pressure on the fuel therein.

Yet. another feature.of thisv invention is found in the provision of a fuel-metering device for a liquid fuel burner having a variable speed rheostat controlled electric motor for a combustion air blower and a fuel line, in which a casing is formed with a pair of separate fuel chambers having fuel communication below the fuel levels therein. An upright tube in one of the fuel chambers is formed with a longitudinally extended fuel-metering slot terminating at the fuel level therein, while the lower end of the tube is connected with the fuel line. A float, movably supported in the second fuel chamber for up and down movement, has a permanent magnet or soft iron shoe therein arranged opposite one end of an electro-magnet or core, respectively, which is carried in the casing wall and projected inwardly of the second fuel chamber. The electro-magnet or core is connected in the circuit of the blower motor such that on an increase in voltage to the blower motor the magnet is repulsed by the electromagnet, or the shoe is attracted by the core, whereby the float is moved downwardly to raise the fuel level in the two chambers. This elevation in the fuel level provides for a flow of fuel through the metering slot in direct proportion to variations in the voltage and speed of blower operation to maintain a desired air to fuel ratio at the urner.

Still a further object of this invention is found in the provision of a fuel system for a liquid fuel burner having a low pressure pump with. an outlet connected to a fuel line for the burner, in which the pump inlet terminates in an upright tubular portion having arrangedtherein an upright fuel supply tube formed with a discharge portion in substantial co-axial alignment with the tubular portion. Below such discharge portion, and within the tubular portion, is a stack of vertically spaced screens. Fuel is supplied to the supply tube so as to flow by the action of gravity downwardly therein for discharge as a small stream or in droplet form. This fuel on hitting the screens is spread thereon, and then drawn through the meshes thereof by the action of the pump, so that on passing through the screens the fuel is in a foam or bubble form. The fuel line is substantially free of any restrictions, and with the pump operating at a low pressure of about two pounds per square inch, the fuel is retained in its bubble or foam form for supply to the burner.

Further objects, features and advantages of this invention will become apparent from the following description when taken in connection with the accompanying drawings, in which:

Fig. 1 is a foreshortened longitudinal sectional view of a space heater, embodying the fuel-metering system of this invention, with certain parts being removed and other parts being shown in elevation to more clearly illustrate its construction and assembly;

Fig. 2 is a transverse sectional view taken along the line 22 in Fig. 1;

Fig. 3 is a plan view of a fuel-metering unit which forms a part of the fuel-metering system of this invention;

Fig. 4 is an enlarged sectional view of the fuel-metering unit as seen along the line 4-4 in Fig. 3 showing the fuel pump in assembly relation therewith;

Fig. 5 is a detail sectional view taken along the line 5-5 in Fig. '4;

Fig. 6 is a detail sectional view as seen on the line 66 in Fig. 5;

Fig, 7 is a detail sectional view taken along the line 77 in Fig. 4;

Fig. 8 is a diagrammatic showing of the air control system for the fuel-metering unit shown in Fig. 4;

Fig. 9 is a sectional view of the fuel-metering unit illustrated similarly to Fig. 4 and showing a modified form of air control system therefor;

Fig. 10 is a sectional view of a modified form of fuelmetering unit, illustrated similarly to Fig. 4 and showing an electrical control therefor;

Fig. 11 is a sectional view of a fuel-metering unit illustrated similarly to Fig. 10 but showing a modified electrical control therefor; and

Fig. 12 is a diagrammatic showing of an electrical circuit which is applicable to the fuel-metering units shown ,inFigs. wand 11.

With reference'to the drawings, the fuel-metering'system of this invention is illustrated in Figs. 1 and 2 in assembly relation with a space heater having a motor compartment 20 and a heat-exchange unit 21 extended horizontally from one side 22 of the motor compartment. A base or stand for the heater is indicated at 23.

blower 27 has an inlet (not shown) open to the atmosphere and an outlet (not shown) open to the motor compartment 20. On operation of the blower 27 therefor, alris supplied to the compartment 20 under pressure so that the motor compartment constitutes an air pressure chamber for a purpose to appear later. A cam and breaker assembly (not shown), which forms part of the heater ignition system, is carried within a housing 28 and is operated by the blower motor 26.

The burner fuel system includes a fuel metering unit 29, which is arranged near the top of the motor compartment 20, and a pump 32 positioned below the fuel-metering unit. The pump inlet 33 is positioned upright within the compartment 20 and is connected by a suitable coupling 34 with the outlet 37 of the fuel-metering unit. The outlet of the pump 32 (not shown) is connected with a fuel line 38 for the burner designated generally at 39. Fuel from a suitable source, located outside of the compartment 20, is supplied to the fuel-metering unit through a fuel supply line 42.

The burner 39 is carried in the compartment side wall 22 and extends outwardly therefrom into a combustion chamber 43 formed within the heat-exchange unit 21, which is of a generally cylindrical shape. The burner 39 is also of a generally cylindrical shape and is concentrically arranged within the unit 21. Spaced about the peripheral wall or casing 44 of the combustion chamber 43, and between such wall and the outer shell 47 of the heat-exchange unit, is a series of heat radiating fins 48, the inner ends 49 of which are spaced from the motor compartment side wall 22 so as to form an annular air manifold 51 between the inner ends of the combustion chamber wall 44 and the shell 47. The air manifold 51 is thus common to all of the air passages formed between adjacent fins 48. A circulating air blower 52 is carried on the top side of the shell 47, and at the inner end thereof, to provide for its outlet 53 being in open fluid communication with the air manifold 51. The inlet 54 of the air circulating blower 52 is open to the atmosphere.

The fins 48 terminate at the outer end wall 56 of the combustion chamber 43 and the shell 47 projects beyond such outer end wall 56 to the outer end wall 61 for the heat-exchange unit 21. An air pressure equalizing chamber is formed between the outer end wall 61 of the heatexchange unit and the outer end wall 56 of the combustion chamber 43 and has a plurality of outlets 64 in the end wall 61.

Spaced outwardly from the compartment side wall 22 and between the combustion chamber wall 44 and the side wall 67 of the burner 39 is an upright annular flat ring 71 which is formed with a series of exhaust openings 72 so that an annular exhaust manifold 73, concentrically arranged within the air manifold 51, is defined by the ring 71, side wall 22, and the inner ends of the combustion chamber wall 44 and burner wall 67. The exhaust gases from the burner thus pass outwardly therefrom, as indicated by the arrows 76 in Fig. 1, centrally of the combustion chamber 43, and upon striking the combustion chamber end wall 56, are deflected to flow in a reversed direction, as indicated by the arrows 77, for flow through the exhaust ports 72, into the exhaust manifold 73, and outwardly from the exhaust manifold through a pair of oppositely arranged exhaust outlets 78.

The coil unit 24 is directly connected with a hot electrode 86 extended outwardly from the motor compartment 20 into the burner 39 at a position in substantial co-axial alignment with the axis of the burner. The inner end-87 of the hot electrode 86 is spaced from and upwardly from the inner end 88 of a ground electrode 89. The end 88 of the electrode 89 terminates in the bottom wall of a cavity 91 formed in a ceramic member 92 mounted about the inner end of the electrode 89. An arc discharge, shown at 95, between the electrode ends 87 and 88, and as effected by the burner ignition system, is directed by the relative spacing between such electrode ends and .the arrangement of the electrode end 88 within the cavity 91, to follow a path adjacent the under side of the top portion 93 of the cavity wall and about the edge or lip 94 of such wall portion 93.

The fuel supply line 38 terminates at a position inwardly of the electrode ends 87 and 88, and above such electrode ends. On the admission of fuel into the burner 39 a part thereof impinges against a deflector arm 96 to be deflected onto the wall portion 93 of the ceramic member 92, with this part of the fuel being acted upon by the heated wall portion 93 and the arc discharge 95 to provide for its vaporization and ignition. The fuel part thus ignited functions as a pilot flame in the starting of burner operation. a

The hot electrode 86 is supported in means including a ceramic member 101 formed with air passages 103 for admitting air directly from the motor compartment or pressure chamber 20 into the burner 39. The burner side wall 67 is of a hollow construction and has its inner end 107 open to the pressure chamber 20, and its inner wall section 108 formed with a plurality of air openings 109, whereby the side wall 67 functions as an air passage for carrying secondary or supplementary combustion air into the burner 39.

The operation of the burner, including the operation of the blowers 27 and 52, and ignition system, is controlled through the provision of means including a temperature control switch 81, a run and stand-by switch 82 and a safety ignition switch 83 which are carried on the motor compartment wall 84 and to the outside thereof for ready accessibility.

The fuel-metering unit 29 (Figs. 1, 3 and 4) includes a casing or housing 111 which is divided into a pair of separate fuel chambers 112 and 113 by the provision of an upright tubular partition member 114 arranged centrally of the casing 111.

Arranged within the fuel chamber 112, and about the fuel chamber 113, is a float 117 of what might be termed a doughnut shape)? The float is secured at 118 to one arm 119 of a bell crank which is pivoted at 122 on the side wall of the casing 111. A second arm 123 of the bell crank is engageable with a valve 124 adapted for seating engagement with a valve seat 126 formed on a fuel inlet 127 for the chamber 112. The inlet 127 is connected with the fuel line 42. The float 117 is thus movably supported for up and down movement within the fuel chamber 112, and with this movement, through the arms 119 and 123, actuating the valve 124 to maintain a predetermined level of the fuel within the chamber 112. The partition member 114 is formed with a series of fuel openings 128 adjacent the lower end thereof, and below a normal level of the fuel in the chambers 112 and 113, so that fuel is permitted to flow from the chamber 112 into the chamber 113 to the same level as the fuel in the chamber 112.

Arranged within the chamber 113, in a concentrically spaced relation with the partition member 114, is an upright tube 129 (Figs. 4, 5 and 6) which is formed with a longitudinally extended slot 131, the lower end 132 of which terminates at substantially the level of the fuel in the chambers 112 and 113, which level is indicated at 130. The lower end of the tube 129 is connected through the coupling 34 with the inlet 33 of the pump 32, as shown best in Fig. 4, so the tube 129 and inlet 33 are extensions of each other.

Arranged within the tube 129 (Figs. 5 and 6) at a position opposite the slot 131 therein, and secured to the tube 129, as by welding, is a metering and fuel supply tube 133 having a laterally offset lower end 134 which terminates in a discharge portion 135 at a position co-axial with the fuel supply tube 129. The tube 133 is formed with a metering slot 137 that is open to the slot 131 in the tube member 129 and substantially coextensive in length with the slot 131.

So long as fuelwithin the chambers 112 and 113 is below the fuel level 130, no fuel is admitted into the metering tube 133., However, upon the raising of the level of the fuelin the chamber 113 above the fuel level 130, and in turn'above the lower end of the metering slot 137, fuel is permitted to flow through the slots 131 and 137 and into the metering and supply tube 133 in an amount proportional to the area of that portion. of the slot 137 included between the normal fuel level and the raised fuel level.

The metering of the fuel throughthe slot 137 in an amount to obtain a desired air to fuel ratio within the burner 39 is accomplished by the provision of means including what might be termed a double-L connection 139 in the top wall 141 of the casing 111 having an upright leg 142 open to the fuel chamber 112 (Figs. 1, 3 and 4). A second leg 143 of the connection 139 is open to the motor compartment or pressure chamber 20, while the third leg 144 is open to the atmosphere. The upper end of the fuel chamber 113 is open to the atmosphere through a tube connection 147. By virtue of these air connections on an increase of the air pressure within the assage-4 is .thus admitted through the slots 131 and "13.7 m an amount proport onal to the pressure of the air in the chamber 20. By virtue of the lowering of the level of the fuel in the chamber 112 below the normal fuel level 130, the float 117'rnoves downwardly, whereby the valve 124 is opened to admit additional fuel into the chamber 112. The metering of the fuel through the slot 137 in proportion to the pressure 'of the air in the chamber 20 is thus continuously maintained during the heater operation.

The atmospheric inlet 144 on the double-L connection 139 is previded with a bleeder valve 148. Adiustment of the valve 148 functions to smooth out any air pulsations created in the'ehamber 2 'by the operation of the combustion air blower 27 and further supplements the function of the metering and supply tube 133 to admit fuel in the burner in an amount to give a desired air to fuel ratio. In other words, with the valve 148 closed, should the amount of 'fuel in proportion to the amount of 'the' air supplied to the burner be excessive, such amount can 'be reduced by opening the valve 148 so as to reduce the effective pressure of the air within the chamber 112 relative to the pressure of the air in the compartment 20.

The fuel admitted to the metering and supply tube 133 'flows downwardly therethrough by the action of gravity and falls from the discharge portion 135 in a small stream or in successive drops. To facilitate the burning of this fuel in the burner 39, the lower end of the tube 129 is provided with a series of stacked small mesh screens 152 which are vertically spaced by the provision of spacer washers 153 arranged therebetween (Figs. 4 and 7). I The fuel from the discharge portion 135, on falling upon the screens 152, tends to spread or distribute itself over the screens by capillary action. The fuel thus spread over the screens is drawn therefhrough by the action of the pump 32 which preferably is of a slow speed, lowpressure reciprocating or diaphragm type. vThis cooperative action of the pump 32 and screens 152 results in the fuel being changed into a bubble or foam form. Since the fuel chamber 113 is open to the atmosphere, the fuel in this form is intimately mixed with air prior to its entry into the pump 32, by virtue of air being enclosed. within the bubbles and surrounding the bubbles.

This bubble form of the fuel is substantially retained by the pump, by virtue of its low speed and low pressure action and with the fuel line 38 to the burner 39 being substantially free of any restrictions, the large part of the fuel admitted to the burner is in a bubble form.

The drawing or suction action of the pump 32 can be varied by the provision of a valve 150 connected in the air line 147 for the fuel chamber 113. When the chamber 113 is not freely open to the atmosphere, as by a partial closing of the valve 150, the action of the pump creates a partial vacuum in the chamber 113 which increases the rise of fuel in this chamber above a normal rise which would be effected only by the air pressure in the fuel chamber112. A regulation of the valve 150 thus provides for a variation in the effective suction action of the pump, which in turn varies the effective action of the air pressure in the fuel chamber 112 relative to the fuel rise in the chamber 113. As a result the metering range of the unit 29 is not only increased, but the metering action is made flexible for the handling of fuels of different viscosities. Stated otherwise, the flow of fuel through the metering slot 137 can be accelerated or reduced, by varying the suction action of the pump 32, so as to correspond with the rate of fuel rise in the fuel chamber 113.

It is seen, therefore, that the width of the metering slot 137 and the height of the fuel level within the chamher 113, above the normal fuel level 130, determines the amount of fuel entering the metering and supply tube 133. During this metering action the fuel level in the chamber 112 is maintained at a predetermined level, above the normal level 130, by the action of the float 117 and valve 124 which function cooperatively to compensate for the fuel flowing into the tube 133. The column of fuel in the chamber 113 to provide a desired air to fuel ratio is readily obtainable by varying the effective pressure of the air in th'e chamber 112 by adjustment of the air bleede r valve 148. As a result, an optimum air pressure within the'cha'mber112 to obtain a desired air to fuel ratio in the burner is positively accomplished, as will be readily apparent from a considerationof the diagrammatic air-control system shown in Fig. 8.

A modified form of air control system for the fuelmetering unit 29 is shown in Fig. 9, which is similar in all respects to the air control system shown in Figs. '4 and 8, except for the provision of a control valve 161 in the leg 1430f the double-L connection 139. With this arrangement, the eifective air pressure within the chamber 112 can be varied by a relative adjustment of the valves 148 and 161 to obtain an optimum pressure within the chamber 112 to give a desired air to fuel ratio at the burner 39. v

The fuel-metering unit 29a, shown in Fig. 10, is similar in all respects to the fuel-metering unit 29, as described in connection with Fig. 4, except for the substitution of an electric control means, in place of the air control 'means, for metering the fuel in response to the supply of combustion air to the burner 39. Similar numerals of reference, therefore, will be used to indicate like parts.

In this modified form the casing 11111 is provided in its top wall 141a with an atmospheric vent 163 for the fuel chamber 112. The fuel chamber 113 is open to the atmosphere, as indicated at 164. The float 117a carries a pole shoe 171, of soft iron, and the casing 111:: carries in its bottom wall 182 an electro-magnet 183, at a position opposite the pole shoe. The pole 184 of the pole shoe is of an opposite polarity relative to the pole 185 of the electro-magnet.

As shown in Fig. 12, the circuit for the electromagnet 183 includes a battery 186, a switch 187, and a variable resistance or rheostat 188 connected in series with the armature 189 and field 190 for the air supply motor 26. The electro-magnet 133 is connected across the motor 26. The effective voltage applied to the electro-magnet 183 is thus variable in direct response to the speed of the combustion air motor 26, with this voltage being increased with a decrease, in the variable resistance 183. Thus, in response to the supply of combustion air to the burner 39, as provided by the blower 27, the float 117a is moved downwardly, by the magnetic attractive force between the poles 184 and 185, in response to an increase in speed of the blower motor 26, whereby to provide for a predetermined metered fuel flow from the chamber 113 through the slots 131 and 137 and into the metering tube 133, as a result of the upward displacement of fuel in the chamber 112 by the downward movement of the float.

The fuel-metering unit 2%, shown in Fig. 11, is similar in all respects to the fuel-metering unit 29a except that the float 117]; is moved up and down by magnetic repulsion rather than by magnetic attraction. The float 11712 carries therein a permanent magnet 191 having a pole 192 at the top side 193 of the float 117b. Extended through the casing top wall 141b is an electro-magnet 194 having a pole 195 of a like polarity relative to the pole 192, and arranged opposite the pole 192.

The electrical circuit for the fuel-metering unit 2% is similar in all respects to the circuit shown in Fig. 12 for the metering unit 29a except for the substitution of the electromagnet 194 for the electro-magnet 183.

Because of the poles 192 and 195 being of a like polarity, an increase in the voltage applied to the electromagnet 194 increases the flux repulsion of the electromagnet 194 whereby to provide for a greater downward movement of the float 117b in response to a voltage increase to the motor 26 and in turn to the speed of operation of the blower motor 26. Since the downward movement of the float 117b displaces a corresponding amount of fuel in the chamber 112, the level of the fuel in the chamber 112 is correspondingly raised to in turn provide for an increase in the level of the fuel in the chamber 113. The float 117b is thus utilized in conjunction with the permanent magnet 191 and the electro-magnet 194 to raise the liquid level in the chamber 113 for passage through the metering slot 137, in response to the supply of combustion air to the burner 39.

Repulsion of the permanent magnet 191 and the float 11712, by the electro-magnet 194, has the same effect as increasing the weight of the float so that the fuel level in the chamber 113 is raised in direct proportion to the fuel displaced by the float, while maintaining the float in a position to open the valve 124. The repelling flux in the electro-magnet 194 is proportional to the applied voltage and the current in the magnet winding. Since this applied voltage and current varies directly with the voltage and current in the blower motor 26, the fuel level in the float chamber 112 will rise and fall in direct response to the speed of the blower operation whereby the fuel admitted to the slot 137 will be metered in an amount to give a desired air to fuel ratio in the burner 39.

Although displacement of fluid by the float has been described and illustrated relative to the application on the float of a magnetic force in response to the voltage applied on the combustion aifmotor, it is to be understood that this displacement can be controlled by electrical means responsive in operation to air pressure variations in the chamber 112 or temperature variations in the heat radiated from the heat exchanger 21.

From a consideration of the above description it is seen that the invention provides for a space heater having a liquid burner with a fuel system and an air combustion system which are operatively associated through a fuelmetering unit to provide for a predetermined air to fuel ratio in the burner. The fuel-metering unit is of a simple and compact construction, having a minimum number of parts, and positive in operation, after initial adjustment, to continuously maintain a metered supply of fuel to the burner. Further, there is provided an air and fuel conditioner which is adapted to receive the metered fuel from the metering unit, and change its form from a solid liquid into a bubble or foam form to facilitate its combustion in the burner. By virtue of the metering slot, and the various adjustments of air pressure to vary the effective air pressure of the combustion air upon the fuel within the fuel chamber 112, the metering unit is readily adapted to meter fuels of varying viscosities and burning characteristics. In one embodiment of the invention eflicient burner operation with a predetermined air to fuel ratio was obtained with fuels varying from aviation gasoline to jet fuels which is a refined fuel oil for use in jet engines.

Although the invention has been described and illustrated with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited since changes and modifications can be made therein which are within the intended scope of this invention, as defined by the appended claims.

We claim:

1. A fuel metering unit for a liquid fuel burner having a supply line for a fuel and air mixture and a variable speed blower for supplying combustion air to said burner comprising, a housing having a pair of separate fuel chambers therein in fluid registration adjacent the lower ends thereof, a tube projected upwardly from the bottom of a first one of said chambers with its upper end open to said first chamber above the level of the fuel therein, an upright metering tube within said upwardly projected tube having a longitudinally extended fuel metering slot therein, said upwardly projected tube having an opening therein in registration with said metering slot to permit fuel from said first chamber to enter said metering tube through said slot, with said opening in said tube being positioned vertically such that the amount of fuel entering said opening varies proportionally with the level of the fuel in said first chamber, a fuel inlet for said second chamber having a float controlled valve, a float in said second chamber operatively connected with said valve to control the level of the fuel therein, means for supplying atmospheric air to said first chamber, a pump means having an inlet and an outlet, with said pump inlet being connected to the lower end of said upwardly projected tube, and said pump outlet being adapted to be connected to said supply line for evacuating air from said first chamber concurrently with supplying fuel from said metering tube to said supply line, and means for varying the level of fuel in said second chamber in response to variations in the speed of said blower.

2. A fuel flow control apparatus for a liquid fuel burner having a variable speed blower for supplying combustion air thereto and a supply line for supplying a fuel and air mixture to said burner comprising, a housing having a fuel chamber therein, an upright tubular member in said chamber, a metering tube in said tubular member arranged so as to receive fuel from said chamber in varying amounts proportional to the level of the fuel in said chamber and discharge said fuel into said tubular member, means for supplying air to said tubular member for mixing with the fuel supplied thereto by said metering tube, means for connecting said tubular member to said supply line for supplying fuel and air thereto, and air passage means connected to said chamber and adapted to be connected to said blower for varying the level of the fuel in said chamber in accordance with the amount of combustion air being supplied by said blower to the burner.

References Cited in the file of this patent UNITED STATES PATENTS 1,733,792 Good Oct. 29, 1929 1,774,714 Lavoie Sept. 2, 1930 1,801,446 Muhr Apr. 21, 1931 1,854,749 Lord Apr. 19, 1932 1,908,432 Long May 9, 1933 1,917,577 Doble July 11, 1933 2,230,911 Russel Feb. 4, 1941 2,367,038 Martin Jan. 9, 1945 

